There’s no point denying that in science is partly an issue of marketing: branding matters. Would we be so interested in gravitationally collapsed stars if they had not been dubbed “black holes”? (The term is generally attributed to the aphoristic American physicist John Wheeler.) Would we care about the non-commutation of certain quantum variables, as the experts would phrase it, if Werner Heisenberg had not called it (once translated from the German) the Uncertainty Principle? Scientists themselves regularly complain about how a trendy new term—nanotechnology, quantum dots, buckyballs, proteomics—creates a bandwagon that bedazzles funding bodies.
There are certainly dangers of that, but there seems nothing intrinsically wrong in coming up with a catchy name that distils an image and fires the imagination. One of the latest, though, has provoked yet more grumbling and accusations of hype from some quarters. And you have to admit that “time crystals” is a term seemingly designed to hook media interest with a whiff of Dr Who zaniness: a phrase that looks almost tailor-made to grace the cover of New Scientist.
When he coined the term in 2012, physicist Frank Wilczek appended another buzzword to the title of his paper: these weren’t just time crystals but “quantum time crystals,” for they derived from the notoriously strange quirks of quantum theory. But time crystals don’t, as you might anticipate, do anything weird to time itself. Rather, they are crystals that exist in time rather than in space, and Wilczek’s paper showed how they might exist at all.
People take notice of Wilczek, a 2004 physics Nobel laureate who displays the kind of magisterial overview of his discipline that is rare now that physics has fragmented into a thousand different sub-branches. To hear Wilczek speak, or to read his recent book A Beautiful Question, is to see ideas connected in a way that persuades you, if only temporarily, that at last you see how it all fits together. And in his 2012 paper on time crystals Wilczek demonstrates where this broad vision can lead you: to inventive new ideas based on premises so apparently simple that you wonder how no one thought of them before.
What defines a crystal is that it has an atomic-scale structure that repeats again and again in space. In short, it is rather…